Research On The Optical Solutions For Sensitivity Promotion Of Fiber Bragg Gratting Based Fabry-Perot Sensors

Because the fiber Bragg grating based fabry perot(FBG-FP)sensing system is simple and reliable,it is more and more important in optical fiber sensing field.Optical fiber accelemeter and optical fiber vector hydrophone can't be small and high sensitivity at the same time because of the size and mechanical resonance.The performance of the FBG-FP system has been enhanced greatly by optical means of matching interference with repeatedly reflected pulses.The main innovation points and results of this thesis are as follows:1.The parameters optimization design of the FBG-FP sensitivity enhancement system has been analyzed.The sensitivity enhancement ability has been verified consistent with theory and the resolution has been improved successfully by 1th to 9th matching interferometers.2.A secondnary chopping amplification and filter scheme has been put forward to break throuth the limit of light intensity attenuation and unbalance.A major breakthrough of the FBG-FP sensitivity enhancement limit has been made successfully.The noise floor of twenty times sensitivity enhancement has been reduced about 11 d B.3.A new active FBG-FP sensitivity enhancement technology has been put forward.It not only can break through the limit of light intensity attenuation and unbalance,but also has a higher level of integration.The noise performance and pulse equilibrium output capacity of the active FBG-FP have been lucubrated.Thirty times sensitivity enhancement has been made by the active FBG-FP system.4.The crosstalk problems in single channel and time-division multiplexing system of FBG-FP sensitivity enhancement system have been studied theoretically.The source,amptitude and frequency spectrum of crosstalk have been studied respectively and system design method has been deduced.The crosstalk theory has been verified by the emulation,a two elements system and a three elements system.The crosstalk of the time-division multiplexing FBG-FP system has been reduced to less than-40 d B.5.A single channel FBG-FP sensitivity enhancement optical fiber accelemeter and a time-division multiplexing FBG-FP sensitivity enhancement vector hydrophone have been developed.The sensitivity of optical fiber accelemeter has been eighteen times enhanced and the resolution has been impoved about 15 d B.The sensitivity of the optical fiber vector hydrophone has been 4 times enhanced and its directivity is very well.